Mechanistic studies on intramolecular C–H trifluoromethoxylation of (hetero)arenes via OCF3-migration

Abstract

The one-pot two-step intramolecular aryl and heteroaryl C–H trifluoromethoxylation recently reported by our group has provided a general, scalable, and operationally simple approach to access a wide range of unprecedented and valuable OCF₃-containing building blocks. Herein we describe our investigations to elucidate its reaction mechanism. Experimental data indicate that the O-trifluoromethylation of N-(hetero)aryl-N-hydroxylamine derivatives is a radical process, whereas the OCF₃-migration step proceeds via a heterolytic cleavage of the N–OCF₃ bond followed by rapid recombination of a short-lived ion pair. Computational studies further support the proposed ion pair reaction pathway for the OCF₃-migration process. We hope that the current study would provide useful insights for the development of new transformations using versatile N-(hetero)aryl-N-hydroxylamine synthons.